1. Field of the Invention
The subject invention relates to a safety needle assembly that can be safely, easily and securely locked in communication with a fitting of an intravenous administration set.
2. Description of the Prior Art
Intravenous sets are widely used in the prior art to provide intravenous fluid communication with a patient. The prior art intravenous set includes a needle cannula for insertion into a vein of the patient. The needle cannula communicates with one end of a flexible plastic tube, while the opposed end of the tube is connectable to a flexible bag or bottle containing a fluid to be administered to the patient.
A prior art intravenous set may also include a fitting to which a hypodermic syringe may be "piggybacked" for administering parenteral drugs to a patient. For example, a Y-site is a Y-shaped plastic fitting having an inlet leg, an outlet leg and an injection leg. The injection leg of the Y-site is covered by a diaphragm which can be pierced by the needle cannula of a syringe carrying the parenteral drug. The injection leg and the outlet leg of the prior art Y-site typically are collinear with one another, while the inlet leg typically is aligned at approximately 30.degree.-45.degree. to the injection leg.
In use, a needle cannula of a hypodermic syringe carrying the parenteral drug to be administered is pierced through the membrane or septum on the injection leg of the Y-site. The hypodermic syringe is used in the standard manner to inject a selected dose of the parenteral drug into the injection leg. The drug is then transported to the patient by the fluid flowing from the inlet leg, through the outlet leg an toward the patient. A hypodermic needle connected to a lower volume intravenous set, sometimes called a piggyback set, is often used for introducing medication through the septum. Although this specification recites providing medication through the septum using a syringe it is understood that many fluid delivery devices can be used to provide secondary fluid to the needle which pierces or passes through the septum.
The potential for accidental needle sticks is further reduced by prior art needle cannulas having a rigid generally cylindrical shield mounted concentrically around the needle cannula. The shield defines a diameter large enough to telescope over an injection leg on an intravenous set as the needle cannula enters the fitting. Some such shields are provided with at least one axial extending opening for receiving the inlet leg of a Y-site as remaining portions of the shield are telescoped over the injection leg. A protective shield of this general type is shown, for example, in U.S. Pat. No. Re. 33,617.
Although prior art protective shields, as described above, can reduce the probability of accidental needle sticks, the open end of the axially extending openings still offer a potential for contact with the needle cannula. Additionally, a source of intravenous fluid intended for connection to a prior art intravenous fitting can be accidentally disengaged either before its initial use or between successive uses, thereby creating the potential for contamination of the needle cannula and/or loss of medication.